/*
 * Licensed to the Apache Software Foundation (ASF) under one or more
 * contributor license agreements.  See the NOTICE file distributed with
 * this work for additional information regarding copyright ownership.
 * The ASF licenses this file to You under the Apache License, Version 2.0
 * (the "License"); you may not use this file except in compliance with
 * the License.  You may obtain a copy of the License at
 * 
 *      http://www.apache.org/licenses/LICENSE-2.0
 * 
 * Unless required by applicable law or agreed to in writing, software
 * distributed under the License is distributed on an "AS IS" BASIS,
 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
 * See the License for the specific language governing permissions and
 * limitations under the License.
 */

package org.apache.catalina.util;

import org.apache.tomcat.util.ExceptionUtils;

import java.io.IOException;
import java.io.InputStream;
import java.util.Locale;
import java.util.Properties;

/**
 * Utility class that attempts to map from a Locale to the corresponding
 * character set to be used for interpreting input text (or generating
 * output text) when the Content-Type header does not include one.  You
 * can customize the behavior of this class by modifying the mapping data
 * it loads, or by subclassing it (to change the algorithm) and then using
 * your own version for a particular web application.
 *
 * @author Craig R. McClanahan
 */
public class CharsetMapper {


	// ---------------------------------------------------- Manifest Constants

	/**
	 * Default properties resource name.
	 */
	public static final String DEFAULT_RESOURCE =
			"/org/apache/catalina/util/CharsetMapperDefault.properties";


	// ---------------------------------------------------------- Constructors
	/**
	 * The mapping properties that have been initialized from the specified or
	 * default properties resource.
	 */
	private Properties map = new Properties();

	/**
	 * Construct a new CharsetMapper using the default properties resource.
	 */
	public CharsetMapper() {
		this(DEFAULT_RESOURCE);
	}


	// ---------------------------------------------------- Instance Variables

	/**
	 * Construct a new CharsetMapper using the specified properties resource.
	 *
	 * @param name Name of a properties resource to be loaded
	 * @throws IllegalArgumentException if the specified properties
	 *                                  resource could not be loaded for any reason.
	 */
	public CharsetMapper(String name) {
		InputStream stream = null;
		try {
			stream = this.getClass().getResourceAsStream(name);
			map.load(stream);
		} catch (Throwable t) {
			ExceptionUtils.handleThrowable(t);
			throw new IllegalArgumentException(t.toString());
		} finally {
			if (stream != null) {
				try {
					stream.close();
				} catch (IOException e) {
				}
			}
		}
	}


	// ------------------------------------------------------- Public Methods

	/**
	 * Calculate the name of a character set to be assumed, given the specified
	 * Locale and the absence of a character set specified as part of the
	 * content type header.
	 *
	 * @param locale The locale for which to calculate a character set
	 */
	public String getCharset(Locale locale) {
		// Match full language_country_variant first, then language_country,
		// then language only
		String charset = map.getProperty(locale.toString());
		if (charset == null) {
			charset = map.getProperty(locale.getLanguage() + "_"
					+ locale.getCountry());
			if (charset == null) {
				charset = map.getProperty(locale.getLanguage());
			}
		}
		return (charset);
	}

	/**
	 * The deployment descriptor can have a
	 * locale-encoding-mapping-list element which describes the
	 * webapp's desired mapping from locale to charset.  This method
	 * gets called when processing the web.xml file for a context
	 *
	 * @param locale  The locale for a character set
	 * @param charset The charset to be associated with the locale
	 */
	public void addCharsetMappingFromDeploymentDescriptor(String locale, String charset) {
		map.put(locale, charset);
	}


}
